Textile drawing frame



Patented Apr. 16, 1946 scarse` `l 'rarer-11,12"piuminoFrattini"j,` f

Roderc `D. Tarr, Biddeford, Maine,l assignor to Saco-Lowell Shops,Boston, Mass., a. corporation I of Maine y `Appucatium May 25,1941i,serial-15m.` 483,331 l [j ly connus. (cris-130)? ffl'his'inventionrelates to drawing frames `of the `type commonly used in the manufactureof` cotton Iyarnl "inf doubling "and drawing strands of f roving or.sliver.l AForexample, `it is a`common practice to double founsix`or'eight strands of card sliver lor roving and to draft them in adrawing frame to produce a single roving which will be*v more uniform incompositionthan were'any of the constituent strands from which it wasmade. Often this doubling and drawing operation is repeated l one ormore times before the resulting roving is taken to th'e next step inthecustomary process `of manufacturing -cotton yarn.

A These drawing frames'comprise a series of pairs of intermeshing utedrolls; positioned one in advance of another, through which the web com-`posed of the rovings is "fed, each successive pair vof rollsbeingdriven at a slightly higher peripheral speed than the preceding pair soas to produce the desired draft. The web issuing from be-V tween thedelivery rolls is gathered and led into a coiler.

In order for such a machine to function properly, the iiuted rolls mustbe manufactured with a high degree of accuracy. This necessarilyincreases materially the expense of manufacture of the machine. Thatsuch accuracy is necessary will be evident from the consideration thatth'e effect of inaccuracy is cumulative as the machine operates. Thatis, if, due to such inaccuracies, one pair of rolls feeds at, say, onethousandth of an inch slower per revolution at one end than at theother, then at the end of one thousand revolutions the error will amountto a length of one inch. While as slight an error as this `will be lostin the draft, a somewhat larger error Vmay well result, in the course ofa few hours run,

in producing a sag in the web between two successive pairs of rolls,thus nullifying the drafting operation at this point. In any event, sucherrors tend to defeat the object of the doubling and drawing process,which ls to produce a strand having greater uniformity than do theoriginal strands.

The present invention deals especially with these considerations, and itaims to devise a drawing frame in which'the desired degree of accuracycanbe obtained more economically and with more certainty.

The nature of the invention will be readily understood from thefollowing description when read in connection withthe accompanyingdrawing, and th'e novel features will be particularly pointed out in theappended claims. n

In the drawing,

Figure 1 is a vertical,4 sectional viewof a' head vof a drawingframewith `some partsshown in elevation; and

` FigureZ is annlalfgd sectional view of cooperating portionsofonepairof therolls illustratedin'Fig. 1. `Referring rstto Fig.` 1, theconstructionthere shown` comprises four pairs of metallicintermeshingrolls including bottom rolls 2, `3, 4 and 5 and top rollscooperating with the respective bottom'rolls and indicated at 6, 1, Band9. The bottom rolls are positively driven byhgearing but the top rollsare driven simply through "their relationship to the `botto`m"rlls` andthrough the interveningflber 'or gristfy Weight hooks |0, Il,

l2 and I3b`ear` on the gudgeons ofthe respective top rolls andj are ofsuchmass as to makeeach.`

pair of rolls grip the web of lbersWith-sumcient pressure foroperatingpurposes. Each successive pair of rolls,\proceeding` from rightto' left, is driven at a suiciently higher speed than the preceding pairto produce thedesired draft. The arrangement shown also includesV theusual hinged top cover I8 equipped with a clearer cloth i9.

So far as the general organization of the construction Just described isconcerned, itmay be exactly like those in common use, and it may beequipped with the usual guides, stop devices, and

oth'eraccessories ordinarily used in drawing` frames. A customaryarrangement is to draw the strands of roving or sliver from supply cansset up at the right-hand side of the machine, to feed them together inthe form ofa web W through the rolls, and then to guide the reduced webissuing from the front'or delivery rolls 2 and 6 into the trumpet of acoller which deposits the drawn strand in a roving canr In some cases,also. one or more of the top rolls 6 and 1 are replaced with smoothsurfaced cushioned covered rolls, and in some machines, also, the numberof rolls is increased. Such changes or modifications are im-` materialfrom the standpoint of the present invention. f

According to this invention one or more of these pairs of rolls arefluted in the manner indicated od, to produce ribs a of `the form thereshown,

and these ribs arev separated by intervening round-bottomed grooves b.After the iluting operations have been oompletedthe rollis ground veryaccurately to a given outside diameter, the

tolerance from oneend to another of the roll being preferably withintwo-thousandths of an inch. 'I'his grinding operation produces smallattened tips c on the rounded ends of the ribs a.

The top roll 9 is also milled, as shown in Fig. 2, to produceround-ended ribs d which are shorter in radial dimensions than the ribsa of the bottom roll, and these ribs d are separated by roundbottomedgrooves e like the grooves b. The utes in both rolls have the samepitch. In making the top roll, however, no eifort is made to obtainextraordinary accuracy in either its inside or outside diameter, but thedepth of ilute is maintained with a high degree of accuracy. In otherwords, the depth of flute is constant from one end to the other, andthis result may be readily produced by making the same milling cutterwhich shapes a rib also form the bottom`A of the adjoining groovesimultaneously. Also, the radius of curvature of the grooves issomewhat, say four or ve-thousandths, larger in the top roll than in thebottom roll. The construction shown in Fig. 2 is drawn substantially toscale and is enlarged on a twenty to one ratio.

The important feature vof this arrangement is that the bottom roll hasaconstant outside diam eter from end to end of the fiber working areathereof, while the top roll has a constant depth of ute throughout itsber working area irrespective of minor manufacturing errors in diameter.Consequently, and because the lower roll is positively driven, and alsobecause a substantial clearance of something in thev order of ten tofourteen-thousandths of an inch is provided between the ilutes of thetop roll and the Walls of the grooves of the .bottom roll, the latterroll controls the rate of feed of the brous web irrespective of thediameter of the top roll. With this construction, therefore, the rolls 9and 5 will produce a 4uniform delivery or rate of feed of `sliver acrosstheir entire ber. engaging surfaces. And this result is produced bythepresence of cooperating features of accuracy in the two rolls which areeasily produced by relatively inexpensive manufacturing operations.

All, or any desired number, of the pairs of rolls in a drawing frame maybe made in this manner. Accordingly. the invention makes it possible toobtain, in a more advantageous manner, those results which have onlybeen obtained heretofore in a drawing frame by the use of manufacturingprocesses considerably more expensive than those required in making therolls above described.

Having thus described my invention, what I desire to claim as new is:

1. In a textile drawing frame, comprising a series of pairs of draftingrolls, mounted one behind another, to operate successively on a webcomposed of parallel 'rovings, certain at least of said pairs of rollsconsisting of driven lower metallic luted rolls and upper metallicfluted rolls, each meshing with and resting upon its respectivecooperating lower roll and being driven thereby, a construction in whichthe outside diameter of one at least of said lower rolls is maintainedwith a high degree of accuracy throughout its fiber working areanotwithstanding normal manufacturing variations in the depths of itsflutes, and

its cooperating top roll has a constant depth of ute throughout vits berWorking area regardless of minor variations in its diameter, the tworolls having the same vpitch of fiuting and being supported in a meshingrelationship but the ribs of the Vtop roll being of smaller radialheight than -those of the bottom roll and having an abnormal- 1y largeclearance with the walls of the grooves of the lower roll even when theribs of the lower roll substantially contact with the bottoms of thegrooves in the top roll.

2. In a drawing frame according to preceding claim l, a construction inwhich said ribs of the lower roll have rounded ends with narrowflattened tops. t

RODERIC D. TARR.

